How get all matching positions in a string?

Question

I have a column flag_acumu in a table in PostgreSQL with values like:

\'SSNSSNNNNNNNNNNNNNNNNNNNNNNNNNNNNSNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN\'         


        

Answer 1

Since you didn't specify your needs to a point in which one could answer properly, I'm going with my assumption that you want a list of positions of occurence of a substring (can be more than 1 character long).

Here's the function to do that using:

• FOR .. LOOP control structure,
• function substr(text, int, int).

---

CREATE OR REPLACE FUNCTION get_all_positions_of_substring(text, text)
RETURNS text
STABLE
STRICT
LANGUAGE plpgsql
AS $$
DECLARE
  output_text TEXT := '';
BEGIN

FOR i IN 1..length($1)
LOOP
  IF substr($1, i, length($2)) = $2 THEN
    output_text := CONCAT(output_text, ';', i);
  END IF;
END LOOP;

-- Remove first semicolon
output_text := substr(output_text, 2, length(output_text));

RETURN output_text;
END;
$$;

Sample call and output

postgres=# select * from get_all_positions_of_substring('soklesocmxsoso','so');
 get_all_positions_of_substring
--------------------------------
 1;6;11;13